Alloy steel



Patented Dec. 25, 1934 PATENT OFFICE ALLOY STEEL Ralph P. De Vries, Menands, N. Y.

No Drawing. Application November 12, 1930,

Serial No. 495,291

9 Claims.

My invention relates to .alloy steels and particularly to a steel of this character which can be hardened by heating the steel to a temperature above its critical point and thereafter cooling it in air. It also relates to alloy steels having high physical properties at elevated temperatures and particularly adapted to resist stress and deformation under such conditions.

Many so-called, air-hardening tool steels have heretofore contained nickel in substantial quantities and while they can be hardened to some extent by cooling in air after heating to a temperature of from 1650 F. to 1800 R, such alloys can not be made sufiiciently hard for many tool and die purposes. Moreover, the nickel contentwhich promotes air hardening makes the alloy very diflicult or impossible to machine.

The presence of from 0.5% to 5% of nickel in my alloy would render it very diflicult if not impossible to machine, and above about 5%, would render the alloy austenitic and non-hardenable.

The principal object of my invention is to provide an air-hardening alloy steel which can be readily machined, thereby adapting it for use in tools and dies, and which does not possess those objectionable characteristics which'are inherent in chromium nickel steels.

Steels made according to my invention may include the following elementswithin the ranges specified. That is to say- Per cent Carbon 0.75 to 1.5 Chromium 3.0 1506.0 Molybdenum 0.5 to3 Tungst v 0.501204 Silicon 0.3 to 1.5 Copper 0.15t0 1.50

In addition to the above mentioned elements 40 manganese may be present in the quantities usually encountered in steel making practice up to say 1%, while sulphur may be present up to as high as 0.20% and phosphorous up to 0.02%.

All of the first mentioned elements contribute in markeddegree to the desired end of obtaining highhardness by heating to proper temperatures and cooling in air. Generally speaking the intensity of the hardening will vary directly with either the molybdenum or the coppercontent, or both. That is, increasing either the molybdenum or copper, orboth, intensifies the hardening while decreasing these elements decreases the intensity of hardening. Thus, if it is desired to maintain equal hardening efiects in various sizes of it can be accomplished by, changing the proportions of the elements in such-a way that the slower cooling in air of the larger sizes is compensated by increasing the molybdenum or copper content, or both.

The following approximate analysis is typical 5 of my invention:

' Per cent Carbon 0.90 Chromium 5. 0 Silicon 1 0 Molybdenum 0. 75

Copper 1.0 Tungsten"; 2.0

Iron Balance It will be noted that the total alloy content in the above analysis approximates about 10% which is distributed among the various elements mentioned, and it will generally be found that a minimum of about 9% or 10% of alloy is necessary to attain the desired results.

The effect of copper is very pronounced in producing air-hardening and, although the full effect thereof will naturally not be obtained with the minimum quantity above specified nevertheless the addition of this quantity does produce appreciable-air-hardening characteristics in the al- I lay. When 0.5% and higher percentages of copper are employed it lowers the temperature at which air-hardening can be obtained. In this respect, the copper in my alloy functions similar to nickel in the ordinary air-hardening steels.

A three and a half inch square bar of this typical analysis when heated to 1750 F.:and thereafter'cooled in air had a hardness of 624- Brinell over the entire surface. So. far as I am aware there has heretofore been no alloy steel having air hardening properties to the extent of becoming 600 Brinell hard or better and which could be hardened at a temperature as low as 1750 F. Obviously, it is a decided advantage to harden at such a low temperature in die steel which must be ground on the surface after the hardening operation is completed. Moreover, the tensile strength of the alloy at elevated temperatures up to 1600 F. is extremely high.

Alloy steel within the given range of my composition will of course become slightly harder when cooled, after heating for hardening, in a medium such as oil, which increases the rate of cooling over that of air. Hence, steels of this 50 alloy can by quenching in oil be hardened to a somewhat greater degree than by cooling in air. For all practical purposes, however it will be more desirable to cool them in air after heating because by this treatment deformation and size changes are avoided to a large extent. When this steel is reheated after hardening from 1750 F. and cooling in air, it first becomes softer, and, as the temperature is progressively raised from 800 F. to 950 F., it becomes harder. This is a suitable drawing temperature for a great many die purposes. I

Because of its high physical characteristics at elevated temperatures and because it has the property of renewing its hardness when cooled in air after being heated to such temperatures, my alloy is particularly adapted for furnace parts, motor valves, hammer dies and other instrumentalities exposed to high temperatures, or where such exposure is oft recurring.

What I claim is 1. An air-hardening alloy steel which can be readily machined and which has high resistance to stress and deformation at high temperature containing as essential alloying ingredients, carbon from 0.75% to 1.5%, chromium from 3% to 6%, molybdenum from0.5% to 3% tungsten from 0.5% to 4%, silicon from 0.3% to 1.5%, and copper from'0'.15% to 1.5%; the remainder being substantially all iron.

2. An air-hardening alloy steel which can be readily machined and which has high resistance to stress and deformation at high temperature; said steel containing a total of more than 9% of the following elements, carbon from 0.75% to 1.5%, chromium from 3% to 6%, molybdenum from 0.5% to 3%, tungsten from 0.5% to 4%, silicon from 0.3% to 1.5%, copper from 0.15% to 1.5%; the remainder being substantially all iron.

3. An air-hardening alloy steel which can be readily machined and which has high resistance to stress and deformation at high temperature; said steel containing a total of more than 9% of the following elements, carbon from 0.90% to 1.30%, chromium from 4.5% to 5.5%, molybdenum from 1% to 2%, tungsten from 0.75% to 3.0%, silicon between 0.50% and 1%, and copper 0.15% to 1.25%; the remainder being substantially all iron.

4. A readily machineable alloy steel having high resistance to stress and deformation at high temperature and which can be air-hardened containing as essential alloying ingredients, carbon from 0.75% to 1.5%, chromium from 3% to 6%, molybdenum from 0.5% to 3% tungsten from 0.5% to 4%, silicon from 0.3% to 1.5%, and copper from 0.15% to 1.5%, and having a sulphur content of from 0.02% to 0.20%; the remainder being substantially all iron.

5. A readily machineable alloy steel having high resistance tostress and deformation at high temperature and which can be air-hardened'containing sulphur from 0.02% to 0.2% and, as essential alloying ingredients, carbon from 0.75% to 1.5%, chromium from 3% to 6%, molybdenum from 0.5% to 3%, tungsten from 0.5% to 4%, silicon from 0.3% to 1.5%, and copper from 0.15% to 1.5%; the total alloy content of the essential ingredients being not less than about 9%, and the remainder being substantially all iron.

6. A readily machineable alloy steel having high resistance to stress and deformation at high temperature and which can be air-hardened; said steel containing sulphur from 0.02% to 0.2%, carbon from 0.75% to 1.5%, and having an alloy content consisting principally of chromium 3% to 6%, molybdenum 0.5% to 3%, tungsten 0.5%

to 4%, silicon 0.3% to 1.5%, and copper from 0.15% to 1.5%, the remainder being substantially all iron.

7.. A readily machineable alloy steel having high resistance to stress and deformation at high temperature and which can be air-hardened; said steel containing sulphur from 0.02% to 0.2%, carbon from 0.75% to 1.5%, and having an alloy content of not less than 9% consisting principally of chromium 3% to 6%, molybdenum 0.5% to 3%, tungsten 0.5% to 4%, silicon 0.3% to 1.5%, and copper 0.15% to 1.5%, the remainder being substantially all iron.

8. A readily machineable alloy steel having high resistance to stress and deformation at high temperature and which can be air-hardened; said steel containing sulphur from 0.02% to 0.2%, carbon from 0.75% to 1.5% and having an alloy content between 9% and 18% consisting principally of chromium 3% to 6%, molybdenum 0.5% to 3%, tungsten 0.5% to 4%, silicon 0.3% to 1.5%, and copper 0.15% to 1.5%, the remainder being substantially all iron.

9. An alloy steel containing as essential alloying ingredients, carbon from 0.75% to 1.5%, chromium from 3% to 6%, molybdenum from 0.5% to 2%, tungsten from 0.5% to 2%, silicon from 0.5% to 1.5%, and copper 0.15% to 1.25%; the remainder being substantially all iron.

RALPH P. DE vRrEs. 

